The A’s knew they would endure some rocky times with the young group of starters they thrust into their starting rotation for this season.

That doesn’t make days like Sunday any easier, as rookie Vin Mazzaro got roughed up in a 7-2 loss to the Toronto Blue Jays before a sparse crowd of 13,070 at the Oakland Coliseum.

The damage was done early, as the right-hander didn’t record his first out until his 30th pitch of the game.

Mazzaro walked three, allowed a two-run home run and two doubles to the game’s first six hitters. By then the Blue Jays led 5-0 and were well on their way to claiming the three-game series after the A’s won Friday’s opener.

“You’ve got to locate and make pitches to get yourself out of jams,” A’s pitching coach Curt Young said. “That first inning definitely was an ambush.”

Less than 24 hours after a packed house buzzed with the festivities of Rickey Henderson Night, the atmosphere couldn’t have been more different inside the Coliseum.

That’s partly because the A’s faced such a big deficit before many fans found their seats.

Just two months ago, Mazzaro dazzled in his first two big league starts, earning back-to-back wins without allowing a run. Since then he’s gone 0-8 with a 7.22 ERA in 10 starts.

The eight-game losing streak is the longest for an A’s pitcher since Dallas Braden dropped eight straight decisions from April 29-Sept. 23, 2007.

Mazzaro is the third pitcher in Oakland history to allow at least six runs in four consecutive appearances. Bill Krueger did it in 1985 and Dave Stewart in 1991.

Mazzaro was asked what he’s gleaned after 12 starts of facing major league hitters.

“For one thing, you can’t miss your spots,” he said. “If you do that, you have to miss better. If you’re gonna (pitch) in, you’ve got to go in hard.”

After walking leadoff man Jose Bautista in the first, Mazzaro tried to run a 2-2 pitch inside on Aaron Hill, who turned on the ball and drilled it to left for a two-run homer.

After a double by Adam Lind and consecutive walks, Alex Rios cleared the bases with a three-run double to left-center.

Mazzaro attributed his early struggles to poor fastball command, but he righted the ship somewhat as his slider began working for him.

He pulled things together enough to last five innings, a fact that manager Bob Geren said Mazzaro could take away as a positive. Mazzaro allowed a run in the second and another in the fifth on Rod Barajas’ solo homer, surrendering seven runs on 10 hits total.

Mazzaro addressed post-game questions from reporters in the same ho-hum manner with which he handled his early success. But Geren said confidence can be a fragile thing when young pitchers struggle.

“It’s the big leagues,” Geren said. “(Mazzaro) came out flying. He dominated. Now he’s having some struggles. We have to make sure he realizes what kind of talent he has and does not lose any confidence.”

Down 6-0 after 1½ innings, the A’s got one run back in the second on Mark Ellis’ RBI single and made it 6-2 in the third when Kurt Suzuki’s single scored Rajai Davis. But that was it against Toronto lefty Ricky Romero (10-4) and two relievers. Romero went seven innings and allowed eight hits.